<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <input class= "btn" type= "button" value= "播放" onclick= "Myonclick()">
    <br>
    <input class = "input" type = "text" value = "0">
    <input class = "add" type = "button" value= "+1" onclick= "Add()">
    <input class = "min" type = "button" value= "-1" onclick= "Min()">
    <br>
    
</body>
<script>
    let btn = document.querySelector(".btn");
    function Myonclick()
    {
        if(btn.value == "播放")
            btn.value = "暂停";
        else
            btn.value = "播放";
    }
    function Add()
    {
        let input = document.querySelector(".input");
        input.value = parseInt(input.value) + 1;
    }
    function Min()
    {
        let input = document.querySelector(".input");
        input.value = parseInt(input.value) - 1;
    }
</script>
</html>